Grain weight (GW) is one of key factors contributing the wheat yield. In wheat, breeding for higher GW becomes an important target. In this study, a population of 198 RILs crossed by C615 and Yangmai13 (YM13) was constructed, followed by genotyping with 90K SNP array and quantifying thousand grain weight at four environmental conditions. By using the genome-wide association scanning (GWAS), QTGW.yaas-1BL derived from C615 was detected in one environment at 12.90 cM on 1BL, which accounted for 3.07% of the phenotypic variances and 0.78 of the additive effect. The second locus QTGW.yaas-6AL derived from Yangmai13 was verified at four environments between 112.70 cM~116.00 cM on 6AL, accounting for 7.63%~10.55% of the phenotypic variances and 1.46~1.51 of the additive effect. Genotyping with functional KASP (Kompetitive allele-specific PCR) markers associating with the grain weight revealed six higher grain weight alleles commonly detected in C615 and YM13, and three alleles that are polymorphic between parents. Collectively, the new grain weight QTL identified will lay the foundation for the genetic studies of grain weight in YM13 and in breeding for high-yielding wheat cultivars.